{"id":892,"date":"2026-06-08T02:29:14","date_gmt":"2026-06-08T06:29:14","guid":{"rendered":""},"modified":"2026-08-16T15:09:32","modified_gmt":"2026-08-16T15:09:32","slug":"molecular-orbital-th-2","status":"publish","type":"post","link":"https:\/\/aboutyou.name\/?p=892","title":{"rendered":"Molecular Orbital Theory"},"content":{"rendered":"

Valence Bond<\/span><\/a> theories do not explain O2<\/sub>‘s magnetic nature; only experiments reveal that. The order in which O2<\/sub> will fill its orbits is: sigma2s, sigma2s*, sigma2p, sigma2p*<\/span><\/span><\/p>\n

Molecular Orbital Theory<\/span><\/a> (MO) claims that O2<\/sub> has unpaired electrons, and thus is magnetic, as liquid O2<\/sub> sticks to a magnet. O2<\/sub> has, in total, 12 valence electrons (each oxygen atom donating 6). <\/span><\/span><\/p>\n

MO theory is a method for determining molecular structure in which e’s are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.<\/span><\/span><\/p>\n

Two electrons will fill each s orbital, while 6 electrons can occupy each p orbital. As per Exclusion Principle, 2 electrons will fill both the 2s and 2s* orbits, 6 electrons will fill the 2p orbital, and that leaves 2 electrons to fill the 2p* orbital. <\/span><\/span><\/p>\n

These two electrons will only partially fill this orbital, and will have parallel spins<\/span><\/a>. Since the rest of the electrons are all paired, the remaining two electrons in the 2p* orbital give the diatomic molecule a net total spin. It does not matter if they are +1\/2 or -1\/2 spins, they will both be the same. Since there is a net spin, O2<\/sub> is paramagnetic. <\/span><\/span><\/p>\n